NxM crosspoint switch with band translation

ABSTRACT

An N×M crosspoint switch allows a signal from any one of the N inputs to be routed to one or more of the M crosspoint switch outputs. The switches within the crosspoint switch can be configured as voltage mode or current mode switches. In voltage mode switching an input to the crosspoint switch is provided to an input device, such as an amplifier, having a low output impedance. The output of the low impedance device is provided to a switch that connects the output of the low impedance device to a high input impedance device, such as a band translation device. In current mode switching, the low impedance output of the input device is connected to selectively activated high isolation transconductance devices having high input impedances. The outputs of the transconductance devices are connected to low impedance devices that operate as summing nodes.

PRIORITY APPLICATIONS

This application claims priority to, and hereby incorporates byreference in their entirety, the following patent applications:

U.S. Provisional Patent Application No. 60/433,066, filed on Dec. 11,2002, entitled INTEGRATED CROSSPOINT SWITCH WITH BAND TRANSLATION;

U.S. Provisional Patent Application No. 60/433,061, filed on Dec. 11,2002, entitled IN-LINE CASCADABLE DEVICE IN SIGNAL DISTRIBUTION SYSTEMWITH AGC FUNCTION;

U.S. Provisional Patent Application No. 60/43,067, filed on Dec. 11,2002, entitled N×M CROSSPOINT SWITCH WITH BAND TRANSLATION;

U.S. Provisional Patent Application No. 60/433,063, filed on Dec. 11,2002, entitled MIXER WITH PASS-THROUGH MODE WITH CONSTANT EVEN ORDERGENERATION.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of electronic devices. Moreparticularly, the invention relates to integrated circuit switches andfrequency translation.

2. Description of the Related Art

Signal distribution systems are typically required to distribute asignal, such as an RF signal to one or more locations within the signaldistribution system. The signal distribution system can bereconfigurable to allow routing of signals to be changed from an initialconfiguration. The reconfiguration of the signal distribution system canoccur on-the-fly, while the system is in use. Reconfiguration of signalrouting paths can be accomplished with switches.

However, switching transients can induce noise onto a signaldistribution system and can affect the signal quality of other signaldistribution paths. Additionally, switch isolation can affect signalquality of other signals in the signal distribution system. Low signalisolation may result in noise in the form of crosstalk from one signalpath contaminating a second signal path. Changes in path loading, as aresult of switching signal paths into and out of a signal path, can alsoresult in increased noise or distortion in the signal path.

Signal distribution flexibility and the ability to reconfigure a signaldistribution system on-the-fly is desirable. Yet signal degradation ofsignals distributed throughout the signal distribution system as aresult of signal routing flexibility is to be minimized if signalquality is to be maintained within the signal distribution system.Within a reconfigurable signal distribution system, it is desirable tomaintain signal isolation, minimize noise contributions including noisecontributed by any switching transients, minimize signal distortion, andminimize current consumption.

SUMMARY OF THE INVENTION

According to one aspect of the invention, an N×M crosspoint switchallows a signal from any one of the N inputs to be routed to one or moreof the M crosspoint switch outputs. The switches within the crosspointswitch can be configured as voltage mode or current mode switches. Involtage mode switching an input to the crosspoint switch is provided toan input device, such as an amplifier, having a low output impedance.The output of the low impedance device is provided to a switch thatconnects the output of the low impedance device to a high inputimpedance device, such as a band translation device. In current modeswitching, the low impedance output of the input device is connected toselectively enabled high isolation transconductance devices having highinput impedances. The transconductance devices operate as switches inthe current mode switching device. The outputs of the transconductancedevices are connected to low impedance devices that operate as summingnodes.

In another aspect, the switches are configured to provide high input tooutput signal isolation in a disabled state and connect the input to theoutput in an enabled state. The switch can provide voltage gain orcurrent gain in the enabled state.

Additionally, in another aspect, the N×M crosspoint switch can beimplemented as a single integrated circuit or can be implemented asmultiple integrated circuits. The use of current mode switching orvoltage mode switching is transparent to the user of the integratedcircuit.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings in which like reference charactersidentify correspondingly throughout and wherein:

FIG. 1 is a functional block diagram of a satellite communication systemconfigured to provide signals from multiple satellites to multiple userdevices.

FIG. 2 is a functional block diagram of an integrated crosspoint switchwith band translation.

FIGS. 3A-3D are functional block diagrams of switches.

FIG. 4 is a functional block diagram of an integrated crosspoint switchwith band translation.

FIG. 5 is a functional block diagram of an integrated crosspoint switchwith band translation.

FIG. 6 is a functional block diagram of an integrated crosspoint switchwith band translation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a functional block diagram of one embodiment of a satellitebased communication system, such as a satellite television system 100.However, the invention is not limited to application in a satellitebased communication system, nor is the invention limited to use in atelevision system. The invention is applicable to any communicationsystem where multiple signals in one or more input frequency bands canbe distributed as signals in one or more output frequency bands to oneor more receivers.

The satellite television system 100 includes one or more satellites 110a-110 c that are set at various different orbital slots. Although threesatellites 110 a-110 c are shown in FIG. 1, any number of satellites canexist in a particular satellite television system 100. The satellitescan operate at different carrier frequencies and polarizations. Thedifferent carrier frequencies and polarizations that can be used by thesatellites 110 a-110 c provide a degree of isolation of one satellitetransmission from another. Additionally, the satellites 110 a-110 c canimplement a directional antenna to provide further signal selectivity.Thus, a receiver can select the signals from a desired satellite, forexample 110 a, by receiving the broadcast signals with a correspondingpolarized antenna oriented in the general direction of the desiredsatellite 110 a and tuning to the desired satellite frequency. Becauseeach satellite 110 a-110 c is configured in a similar manner, a moredetailed description is provided for only one of the satellites 110 a.

A satellite 110 a in a satellite television system 100 can include asingle transponder (not shown), but typically includes multipletransponders. Each of the transponders typically transmits at adifferent frequency and has an associated polarization. Two differenttransponders on the same satellite 110 a can transmit on the samefrequency but with different polarities if the selectivity provided bythe difference in polarities is sufficient for the system. If eachtransponder transmits at a different frequency, the differenttransponders on a single satellite 110 a can all transmit with the samepolarity, or can use different polarities.

Additionally, some transponders can be configured with multiple carrierfrequencies having various channel offsets. Other transponders maymultiplex numerous digital channels on a single carrier. The integratedcrosspoint switch with band translation described below can beconfigured to operate over one or more frequency bands with anytransponder modulation type.

For example, a satellite 110 a can include a first transponder thatprovides information on multiple carrier frequencies, with the carrierfrequency spacing corresponding to a channel spacing for a televisionreceiver. The transponders in a satellite 110 a are typically arrangedas transponder groups. For example, the transponder group can beconfigured to provide a contiguous group of channels. Alternatively, thesignals in a particular transponder group can have varied channeloffsets, with one or more channels having different carrier bandwidthsor symbol rates. Additionally, the transponders in a satellite group canbe configured to all transmit using the same polarization. A typicalsatellite 110 a configured for a satellite television system 100 caninclude two transponder groups having sixteen transponders in eachtransponder group, with each group having a different polarity. Ofcourse, the satellite 110 a is not limited to any particular transponderconfiguration, nor are transponder groups necessarily limited to sixteentransponders.

A satellite 110 a configured to operate in a satellite television system100 typically transmits downlink signals in one of two frequency bands.Each frequency band can include one or more channels corresponding toone or more transponders. A first downlink frequency band is in theC-band and typically spans 3.6-4.2 GHz. A second downlink frequency bandis in the Ku-band and typically spans 10.7-12.75 GHz. Of course, eachsatellite or some other signal source may transmit signals over one ormore frequency bands. The frequency bands are not limited to the twolisted frequency bands, and may be any suitable frequency bands,including one or more frequency bands that have yet to be defined andallocated by regulating bodies.

Of course, the upper and lower band edges for the one or more downlinkfrequency bands are not absolutes because of the practical limitationson constructing a brick wall filter. Rather, the frequency bandstypically represent passbands and the operating transponder downlinkfrequency band typically comprises a frequency band that includes afrequency band having the upper and lower band edges within thepassband. Alternatively, the band edges can define stop band edges andthe transponder can transmit a substantially diminished energy outsideof the band edge frequencies. Thus, practically, the downlink frequencybands can span about, or substantially, 3.6-4.2 GHz and 10.7-12.75 GHz.Additionally, while a satellite 110 a can be configured to use aparticular downlink frequency band, the satellite 110 a may not actuallytransmit signals at all frequencies within the downlink frequency band.A satellite 110 a is not limited to transmitting a downlink signal inthese two frequency bands, and there can be additional downlinkfrequency bands implemented by the satellite 110 a. These additionaldownlink frequency bands can be distinct from the previously describeddownlink frequency bands or can overlap some or all of the previouslydescribed downlink frequency bands.

The downlink signals transmitted by the satellites 110-110 c can bereceived by a terrestrial television system and displayed to one or moretelevisions 170 a-170 c. An antenna 120 is typically used to receive thesignals from the satellites 110 a-110 c. The antenna 120 is shown inFIG. 1 as a dish antenna but other antenna 120 configurations can alsobe used. In the embodiment implementing a dish antenna 120, a reflectorcan direct the downlink signals to an antenna feed 122. Although theantenna 120 is shown with only one antenna feed 122, one or more antennafeeds 122 can be implemented on a single antenna 120. Some antennaconfigurations suitable for operation within the system can not includean antenna feed 122. The antenna 120 or antenna feed 122 can beconfigured to receive signals from a particular downlink frequency bandor a particular polarization. For example, the antenna 120 and antennafeed 122 can be configured to receive the 10.7-12.75 GHz frequency bandhaving a left hand circular polarization. Another antenna feed (notshown) included as part of the antenna 120 can be configured to receiveanother downlink frequency band having the same or differentpolarization. Additionally, although one antenna 120 is shown in FIG. 1,multiple antennae can be implemented in a location or multiple locationsas part of a single system.

The output from the antenna 120 is connected to a receiver 180 that isused to process the received signals. In a typical satellite televisionsystem 100 the receiver 180 includes low noise amplifiers that amplifythe signals while minimizing the associated noise contribution.Additionally, the signals received at the satellite downlink frequenciesare typically frequency translated to one or more predeterminedfrequency bands, or common Intermediate Frequency (IF) bands. Thereceived downlink signals can also be filtered to remove out of bandsignals that can contribute interference.

In one embodiment the carrier frequency spacing of the downlink signalstransmitted by the satellites 110 a-110 c typically corresponds to achannel spacing used by a television receiver or a set top box. In thisembodiment, it can be advantageous to frequency convert the entirereceived downlink frequency band to one of the predetermined frequencybands used by television receivers or set top boxes. Alternatively, thereceived downlink frequency band can be frequency converted topredetermined frequency bands at intermediate frequencies for furtherprocessing prior to conversion to frequencies compatible with televisionreceivers or set top boxes. In another embodiment, several channels maybe multiplexed using a single carrier. In this embodiment, one or moremultiplexed carriers can be frequency converted to input frequencies ofa set top box.

The process of low noise amplification, filtering and initial frequencyconversion can be performed by low noise block converters (LNB) 130a-130 c. Three LNB's are shown in FIG. 1, though fewer or more can beused. A LNB, for example 130 a, can be configured to receive signalsfrom one or more antennae, for example 120, amplify, filter, and blockfrequency convert the signals to a common IF band. A first set ofdownlink signals, such as those from a first transponder group, can beblock converted to a first common IF band and a second set of downlinksignals, such as those from a second transponder group, can be blockconverted to a second common IF band. For example, the LNB 130 a canreceive downlink signals from two transponder groups. The multiplesignals from two transponder groups can be received at one or moreantennae 120, or one or more antenna feeds 122. Additionally, thedownlink signals can originate from one satellite, for example 110 a, ormore than one satellite 110 a-110 c.

For example, the LNB 130 a can block convert the signals from the firsttransponder group to a common IF band of 950-1450 MHz. Similarly, theLNB 130 a can simultaneously block convert the signals from the secondtransponder group to a common IF band of 1650-2150 MHz. The blockconverted signals at the two common IF bands can be combined prior tobeing output from the LNB 130 a. This process of block converting twotransponder groups to different predetermined frequency bands and thencombining the signals from the predetermined frequency bands is commonlyreferred to as band-stacking. In the previous example, the band stackedoutput from the LNB 130 comprises block converted transponder signals ina first common IF band at 950-1450 MHz and block converted transpondersignals in a second common IF band at 1650-2150 MHz. Conceivably, basedon the channel spacing and carrier bandwidths employed in particulartransponder groups, signals from two transponder groups can be blockconverted to the same common IF band and combined without having twochannels assigned to the same carrier frequency. Typically, twoindependent signals would not be combined at the same IF carrierfrequency because each would appear as an interference source for theother, potentially making both signals unresolvable. In systems such asTDM or CDM systems, two signals can occupy the same frequency space andstill be independently resolvable provided they occupy different spacesin other dimensions, such as time or code.

If the number of transponder groups exceeds the number of predeterminedfrequency bands, or common IF bands, it may not be possible toband-stack the signals from all of the transponder groups. In such asituation, the band-stacked output from a particular LNB 130 a mayconstitute only a subset of all available transponder groups. AdditionalLNB's 130 b-130 c can be used to ensure that signals from all of thetransponder groups are represented in one of the band-stacked outputs ofthe LNB's 130 a-130 c. However, the band-stacked outputs of the LNB's130 a-130 c are not limited to having signals from distinct transpondergroups. Thus, one or more of the band-stacked LNB outputs can havesignals in common with another of the band-stacked LNB outputs. In otherembodiments, band-stacking is not used, and each transponder group isoutputted from the LNB independently.

The outputs from the LNB's 130 a-130 c are connected to the input of aswitch configuration, referred to herein as an N×M crosspoint switch140. The N×M crosspoint switch 140 includes N inputs and M outputs.Signals from each of the N inputs can be selectively routed to any ofthe M outputs. Thus, the band-stacked output from a first LNB 130 a canbe connected to a first input of the crosspoint switch 140 and can beselectively routed to any of the outputs of the crosspoint switch 140.

The crosspoint switch 140 can be configured such that only one input canbe selectively routed to an output. Alternatively, the crosspoint switch140 can be configured to selectively route more than one input to thesame output. Additionally, the crosspoint switch 140 can also beconfigured such that an input signal can be selectively routed to onlyone output. Alternatively, the crosspoint switch 140 can be configuredto selectively route an input signal to more than one output. Typically,the crosspoint switch 140 is configured to selectively route an input toa single output and only one input can be routed to the particularoutput. Where the crosspoint switch 140 configuration limits one outputto one input, there can be some inputs that cannot be routed to outputsif the number if inputs, N, is greater than the number of outputs, M.Similarly, some input signals can not be able to be routed to an outputif the crosspoint switch 140 configuration limits an output to a signalfrom only one input, and one input can be routed to multiple outputs.

Conversely, some outputs can not have any signals routed to them if thecrosspoint switch 140 configuration only allows one input to be routedto one output and the number of inputs, N, is less than the number ofoutputs, M. Similarly, some outputs may not have any signals routed tothem if multiple inputs can be routed to the same output and an inputcan only be routed to one output. The crosspoint switches in each of theembodiments can be configured in the various alternatives discussedabove.

Each of the outputs of the crosspoint switch 140 is coupled to acorresponding input to a band translation section 150. The bandtranslation section 150 can represent an integrated device that isconfigured to independently provide frequency band translation tosignals at each of its inputs. Alternatively, the band translationsection 150 can represent a collection of one or more band translationdevices that are configured to frequency band translate signals at eachof the inputs. In one embodiment, the band translation section 150 caninclude one or more band translation devices configured to frequencyband translate one or more signals using a common local oscillator. Inanother embodiment, the band translation section can include one or moreband translation devices configured to independently frequency bandtranslate each of the input signals.

In one embodiment, a band translation device within the band translationsection 150 has an input connected to an output of the crosspoint switch140. An output of the band translation device represents an output ofthe band translation section 150. The band translation device can beconfigured to selectively couple an input signal directly to the outputwith no frequency translation, or alternatively to frequency translatethe input signal to an output signal at a frequency band that differsfrom the input frequency band. The frequency translation device canfurther be configured, such that when frequency translation is selected,to selectively frequency translate the input signal from a first one ofthe predetermined frequency bands to a second one of the predeterminedfrequency bands.

In the satellite television embodiment described above, there are twopredetermined frequency bands. A first predetermined frequency bandspans 950-1450 MHz and the second predetermined frequency band spans1650-2150 MHz. In this embodiment, a band translation device canfrequency translate an input signal at one of the two predeterminedfrequency bands to an output signal at one of the same two predeterminedfrequency bands. It can be seen that there are four distinctpossibilities. An input signal in the lower of the two predeterminedfrequency bands, 950-1450 MHz, can be frequency translated by the bandtranslation device to either the lower, or the upper, of the twopredetermined frequency bands. Thus, in the example, the signal outputfrom the band translation device can be in the lower predeterminedfrequency band, 950-1450 MHz, or the upper predetermined frequency band,1650-2150 MHz. Of course, in one of the conditions, there is nofrequency translation, but rather, the input signal is coupled directlyfrom the input of the band translation device to the output of the bandtranslation device. The direct coupling from input to output withoutfrequency translation can be referred to as a pass through state.

Similarly, an input signal provided to the band translation device atthe upper frequency band can be output from the band translation deviceat the upper frequency band or the lower frequency band. In one statethe band translation device is configured in pass through and in theother state the frequency translation device is configured to frequencytranslate the input signal.

The band translation section 150 can be configured to combine theoutputs from one or more band translation section. Alternatively,external components (not shown) can combine one or more band translationdevice outputs.

Thus, a receiver 180 can implement the LNB's 130 a-130 c, the crosspointswitch 140, and the band translation section 150. The receiver 180 canimplement all of these elements in a single integrated circuit or canimplement one or more of the elements on separate integrated circuits orstand-alone devices. For example, the LNB's 130 a-130 c can each beimplemented as stand-alone devices and the crosspoint switch 140 withthe band translation section 150 can be implemented on a singleintegrated circuit. The LNB's 130 a-130 c, crosspoint switch 140 andband translation section 150 can be implemented in a single housing.This arrangement can be particularly advantageous where size of thecomponents is of concern. Additionally, combining the crosspoint switch140 with the band translation section 150 onto a single integratedcircuit can greatly reduce the power requirements over a discreteconfiguration. Reducing the power requirements can result in additionaladvantages. For example, an integrated circuit crosspoint switch 140 andband translation section 150 having reduced power requirements may allowa system with a smaller power supply. Additionally, reduced powerconsumption typically corresponds to reduced heat dissipation. A systemhaving reduced heat dissipation requirements can often use smallerheatsinks or may eliminate heatsinks. The use of smaller heatsinks canfurther reduce the size of the system. Additionally, an integratedcircuit embodiment can advantageously have reduced cost as compared to adiscrete system. The cost savings can be attributable to savings incomponents and materials that can be minimized or eliminated when thecrosspoint switch 140 and band translation section 150 are configured asan integrated circuit.

In another receiver 180 embodiment, portions of the crosspoint switch140 and portions of the band translation section 150 can be implementedon separate integrated circuits and one of the integrated circuits canbe packaged within a LNB, for example 130 a. In still another receiver180 embodiment, the LNBs 130 a-130 c can be housed in a device that isremote from the crosspoint switch 140 and band translation section 150.

The outputs of the band translation section 150, and thus, the outputsof the receiver 180, are coupled to corresponding inputs of set topboxes 160 a-160 c. In the embodiment described, the predeterminedfrequency bands do not correspond to typical television receiver bands.Thus, the set top boxes 160 a-160 c can further frequency translate thesignals to television receiver operating bands. Additionally, the outputsignals from the band translation section 150 can be in a format that isnot compatible with standard television receivers 170 a-170 c. The settop boxes 160 a-160 c can then function as signal processing stages. Forexample, the satellite downlink signals can be digitally modulated in aformat that is not compatible with a typical television receiver 170a-170 c. The set top boxes 160 a-160 c can be configured to demodulatethe digitally modulated signals, process the demodulated signals, andthen modulate a television channel carrier frequencies with the signalsfor delivery to television receivers 170 a-170 c.

Alternatively, if the signals output from the band translation section150 are in a format and are at a frequency band that is compatible withtelevision receivers 170 a-170 c, the set top boxes 160 a-160 c may notbe required. In still another alternative, one or more of the functionsperformed by the set top boxes 160 a-160 c can be integrated into thetelevision receivers 170 a-170 c.

In the embodiment described in FIG. 1 and in the embodiments describedin the other figures, each of the television receivers 170 a-170 c canbe connected to an output from one of the set top boxes 160 a-160 c.Each of the set top boxes 160 a-160 c can have one or more individuallyprogrammable outputs. However, more than one television receiver 170a-170 c can be connected to an output from a single set top box, forexample 160 a. Alternatively, outputs from more than one set top box 160a-160 c, or multiple outputs from one set top box such as 160 a, can becombined or otherwise connected to a single television receiver, forexample 170 a, although such a configuration is not typical. Atelevision receiver, for example 170 a, can be configured to tune to aparticular channel within the one or more frequency bands provided bythe set top box, such as 160 a. The television receiver 170 a canprocess the signal from the selected channel to present some mediacontent, such as video or audio, to the user.

A user is typically provided control, such as through a remote controlfor the television 170 a or set top box 160 a, to selectively configurethe crosspoint switch 140 or band translation section 150. For example,a user can be allowed to select, using a remote control configured tooperate with the set top box 160 a, to receive signals from two distinctsatellite transponder groups.

One of the satellite transponder groups can be received and frequencyconverted to a common IF band using the first LNB 130 a. The first LNB130 a can be configured to frequency convert the signals to the upper IFband, 1650-2150 MHz. The second of the satellite transponder groups canbe received and frequency converted to a common IF band using the NthLNB 130 c. The Nth LNB 130 c can also be configured to frequency convertthe signals to the upper IF band, 1650-2150 MHz. The LNB's of the otherembodiments can be similarly configured. Thus, the block convertedsignals from the two transponder groups would ordinarily not becombinable if any two channels in the two transponder groups sharesignal bandwidths in the common IF bands.

However, in this example, the crosspoint switch 140 can be configured bycontrol signals to output the signals from the first LNB 130 a to afirst crosspoint switch output and to output the signals from the NthLNB 130 c to a second crosspoint switch output. The band translationsection 150 can then be configured, using the control signals providedby the set top box 160 a, to pass frequency translate the signals fromthe first switch output from the upper IF band to the lower IF band. Theband translation section 150 can also be configured to pass through thesignals from the second switch output without frequency translation. Acombiner within the band translation section can be configured tocombine the output signals from the first and second band translationoutputs. The composite signal then includes the signals from the firsttransponder group, located at the upper common IF band, and the signalsfrom the second transponder group, located at the lower common IF band.

Thus, the example can be generalized to allow signals from any N signalsources, which can be satellite transponder groups, to be combined to Mdistinct band stacked signals. The band stacked signals can each includefrom one to M distinct frequency bands. Each of the band stacked signalscan then be delivered to a set top box, multiple set top boxes, or oneor more other receivers for presentation to one or more users.

For example, an output from a first output of the receiver 180 can becoupled to one or more set top boxes, for example 160 a and 160 b.Alternatively, multiple receiver 180 outputs that have information inmutually exclusive bands can be power combined and coupled to a singlecable or distribution system for delivering the signal to one or moreset top boxes or receivers. In still another embodiment, the crosspointswitch 140 may direct the same input signal to two separate inputs ofthe band translation section 150. The band translation section 150 maythen frequency translate a portion of the input to a first frequencyband and may also frequency translate a second portion of the inputsignal to a second frequency band. The two frequency bands can becombined into a signal that is directed to a single cable ordistribution system. In still other embodiments, two separate LNB's withtheir own crosspoint switch with band translation section 150 havingoutput signals in separate frequency bands can have their signals powercombined at the LNB outside the house. In some embodiments, the LNBs 130a-130 c, crosspoint switch 140 and band translation section 150 areimplemented as a single device that may be placed, for example, at theantenna 120. In other embodiments, the LNBs 130 a-130 c may beimplemented in a first device and the crosspoint switch 140 and bandtranslation section can be implemented as one or more devices that canbe located locally or remotely from the LNBs.

The LNB's 130 a-130 c, crosspoint switch 140, band translation section150, and set top boxes 160 a-160 c can be assembled in many differentconfigurations. In each configuration, multiple independent users caneach select different channels from one or more independent signalswithout affecting other users or devices.

FIG. 2 is a functional block diagram of a crosspoint switch with bandtranslation 200. A two input and two output version of the receiver 180of FIG. 1 can be implemented with the crosspoint switch with bandtranslation 200 of FIG. 2 in combination with two LNB's. For example,the receiver of FIG. 1 can include LNB modules connected to anintegrated circuit implementation of the crosspoint switch with bandtranslation 200. This configuration of a receiver allows signal routingand band translation to be performed at a location physically close tothe LNBs. The physical proximity of LNBs to the crosspoint switch withband translation 200 minimizes the loss and induced noise experienced bythe received signals.

The crosspoint switch with band translation 200 is not limited to havingonly two inputs and two outputs. Other embodiments of the crosspointswitch with band translation 200 can include additional inputs andoutputs. The number of inputs can be generalized to any number, N. Thenumber of inputs, N, can be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, or some other number. Similarly, the number ofoutputs can be generalized to any number, M. The number of outputs, M,can be, for example, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26,28, 30, 32, or some other number.

Additionally, the crosspoint switch with band translation 200 can belocated remote from a signal source, such as an antenna or LNB modules.For example, one or more coaxial cables can couple the outputs from LNBmodules to inputs of the crosspoint switch with band translation 200. Inan example environment such as signal distribution within a residence,the LNB modules can be a distance of more than 250 feet away from thecrosspoint switch and can couple to the LNB modules with coaxial cables.

The crosspoint switch with band translation 200 can be configured usingdifferential signal interconnections to improve signal isolation. Thedevice can be implemented with single ended signal interconnections butdifferential signal interconnections typically provide greaterisolation. Signal isolation is of greater concern when the device isimplemented in a single integrated circuit.

The crosspoint switch with band translation 200 has a first signal pathand a second signal path. The first signal path includes a first lownoise amplifier (LNA) 210 a connected to an arrangement of switches, 222a, 224 a, 226 a, and 228 a, that can selectively route a signal at theoutput 214 a of the LNA 210 a to a first band translation device 230 aor a second band translation device 230 b. The crosspoint switch withband translation 200 of FIG. 2 is configured to provide voltage-modeswitching of the signals.

The first LNA 210 a is configured with a differential input 212 a and adifferential output 214 a. The differential input 212 a of the first LNA210 a can be, for example, matched to 75 ohm differential. Thedifferential output 214 a of the first LNA 210 a is configured to have alow impedance. The crosspoint switch with band translation 200 maximizessignal isolation and minimizes switching transients by connecting a highisolation switch configuration to the output of the first LNA 210 a.Band translation devices 230 a, 230 b having high input impedances areconnected to the outputs of the switch configuration.

In one embodiment, a low output impedance refers to a typical magnitudeless than 10 ohms differential. In other embodiments, low impedances mayrefer to other impedance magnitudes that may be higher or lower than 10ohms, and need not be defined differentially. For example, a lowimpedance can refer to a magnitude of substantially less than 33 ohms.In another embodiment, a high impedance refers to a magnitude oftypically greater than 1 kohm differential. In other embodiments, highimpedances may refer to other impedance magnitudes that may be higher orlower than 1 kohm, and need not be defined differentially. For example,in another embodiment, high impedance can refer to a magnitude oftypically greater than 330 ohms. In general the terms low impedance andhigh impedance are defined relative to one another. That is, highimpedance is defined to be greater than or equal to approximately tentimes the low impedance value. Thus, for a low impedance value of 33ohms, a high impedance value is greater than approximately 330 ohms.

The in-phase output of the first LNA 210 a is connected to switches 222a and 224 a that selectively switch the signal to the in-phase inputs ofthe band translation devices 230 a, 230 b based on switch controlsignals provided by, for example, the controller in the set top box 160a of FIG. 1. In an alternative embodiment, a microprocessor local to, orintegrated with the crosspoint switch with band translation 200 canprocess signals, such as one or more control messages, from anassociated set top box or receiver. The inverted phase output of thefirst LNA 210 a is connected to switches 226 a, 228 a that selectivelyswitch the signal to the inverted inputs of the band translation devices230 a, 230 b. A switch connected to the in-phase output, for example 222a, is typically paired with a switch on the inverted output, for example226 a, such that a differential signal is selectively connected by theswitch pair 222 a, 226 a.

Thus, the controller in the set top box can direct a first switch pair226 a, 226 a to selectively connect the differential output of the firstLNA 210 a to the differential input of the first band translation device230 a. A second switch pair 224 a, 228 a selectively connects thedifferential output of the first LNA 210 a to the second bandtranslation device 230 b.

The first band translation device 230 a can selectively frequencytranslate the signal at its input to an output frequency band. The firstband translation device 230 a uses a signal from a first LocalOscillator (LO) 240 a to perform the frequency translation.

A second signal path is configured similar to the first signal path. Asecond LNA 210 b has a differential input 212 b and a differentialoutput 214 b. The signal at the differential output 214 b of the secondLNA 210 b is selectively connected to the first band translation device230 a using a third switch pair 222 b, 226 b. The signal at thedifferential output 214 b of the second LNA 210 b is selectivelyconnected to the second band translation device 230 b using a fourthswitch pair 224 b, 228 b.

Typically, the signals from the first LNA 210 a and the second LNA 210 bare not switched to the same band translation device, for example 230 a.The output of a single LNA 210 a can be switched to both bandtranslation devices 230 a, 230 b while the other LNA signal is notprovided to any of the band translation devices 230 a, 230 b.

The crosspoint switch with band translation 200 is configured to providehigh signal isolation between the input signals and the output signalsfrom the LNA's 210 a and 210 b, and high isolation through thecrosspoint switch section 222 a-228 b. Additionally, the crosspointswitch with band translation 200 provides high signal isolation at theinput and output of the band translation devices 230 a and 230 b.Additionally, the crosspoint switch with band translation 200 has highsignal isolation and low switching transients. Low switching transientsare achieved through the use of low impedance at the LNA outputscombined with high impedance inputs at the band translation devices 230a, 230 b. High signal isolation is achieved using differential signalconfiguration and is also achieved through the use of high isolationswitches.

High signal isolation typically refers to greater than 30 dB ofisolation. It may be advantageous to achieve a high signal isolationthat is greater than approximately 40 dB. In general, high signalisolation can refer to greater than 20 dB, 25 dB, 30 dB, 35 dB, 40 dB,45 dB, 50 dB or some other greater level of isolation.

FIGS. 3A-3D are embodiments of high isolation switches. Each of theswitch embodiments of FIGS. 3A-3D are single-ended configurations. Theswitch embodiments can be duplicated to allow switching of in-phase andinverted signals of differential signals. Thus, a pair of switches fromFIGS. 3A-3D can be used as the switch pairs of FIG. 2.

FIG. 3A is a first switch embodiment having a single transistor 302controlled to selectively connect a signal from its input to its outputbased on the signal applied to the control input. The transistor 302 canbe controlled to selectively isolate a signal at its input from itsoutput based on the signal applied to its control input. Signalisolation is controlled by the ability of the transistor 302 to isolatethe input from the output. A pair of transistors 302 can be used toswitch differential signals.

FIG. 3B is a second switch embodiment. A signal is input at the base ofa first transistor 310 configured as an emitter follower. Additionally,a bias voltage, which is typically a DC bias voltage, is applied to thebase of the first transistor 310. The emitter of the first transistor310 is selectively biased with a controllable current source 312. Thefirst transistor 310 selectively couples a signal from its base to itsemitter when the controllable current source 312 conducts. Conversely, asignal at the base of the first transistor 310 is isolated from theemitter when the controllable current source 312 is off. A pull updevice 314 connects the emitter of the first transistor 310 to a voltagethat is greater than the bias voltage, for example (V_(b)+1V) to ensurethe first transistor 310 is cut off when the controllable current source312 is off.

FIG. 3C is a third switch embodiment having multiple transistorsconfigured to provide increased signal isolation. A signal is providedto a first transistor 320. The output of the first transistor 320 isconnected to an input of a second transistor 322. The output of thesecond transistor 322 is the output of the switch. A third transistor324 is connected to the output of the first transistor 320 and isconfigured to selectively couple the output of the first transistor 320and input of the second transistor 322 to ground or signal return.

A differential control signal is used to control the third switchembodiment. An in-phase control signal controls the first transistor 320and second transistor 322. An inverted control signal controls the thirdtransistor 324. Thus, when the first and second transistors 320, 322 arecontrolled to be conducting, the third transistor 324 is controlled tobe cut off. Conversely, when the first and second transistors 320, 322are controlled to be cut off, the third transistor 324 is controlled tobe conducting.

FIG. 3D is a fourth switch embodiment. The fourth switch embodiment issimilar to the second switch embodiment with additional transistorsconfigured to provide additional signal isolation.

A signal is input at the base of a first transistor 330 configured as anemitter follower. Additionally, a bias voltage, V_(b), which istypically a DC bias voltage, is applied to the base of the firsttransistor 330. The emitter of the first transistor 330 is selectivelybiased with a controllable current source 332. The first transistor 330selectively couples a signal from its base to its emitter when thecontrollable current source 332 conducts. Conversely, a signal at thebase of the first transistor 330 is isolated from the emitter when thecontrollable current source 332 is off.

A second transistor 334 is configured to selectively pull up the emitterof the first transistor 330 to a voltage that is greater than the biasvoltage, for example (V_(b)+1V), to ensure the first transistor 330 iscut off when the controllable current source 332 is off. Additionally,the second transistor 334 can also shunt any signal leakage at theemitter node to AC ground via the bias point, thus improving signalisolation. A third transistor 336 has an input connected to the emitterof the first transistor 330 and an output that is the output of theswitch. The third transistor 336 is selectively controlled to couple thesignal from the emitter of the first transistor 330 to the switch outputwhen the controllable current source 332 is conducting. The thirdtransistor 336 is selectively controlled to isolate the signal from theemitter of the first transistor 330 when the controllable current sourceis off.

FIG. 4 is a functional block diagram of a crosspoint switch with bandtranslation 400 that can also be integrated as a portion of the receiver180 of FIG. 1. A two input and two output version of the receiver 180 ofFIG. 1 can be implemented with the crosspoint switch with bandtranslation 400 of FIG. 4 in combination with two LNB's.

The crosspoint switch with band translation 400 is similar to thecrosspoint switch with band translation 200 of FIG. 2 with the exceptionthat the device of FIG. 4 uses current mode switching while the deviceof FIG. 2 uses voltage mode switching. Thus, the crosspoint switch withband translation 400 can be used interchangeably with the device of FIG.2. However, in some instances, current mode switching can beadvantageous because of the ability to sum currents into a common node.

The crosspoint switch with band translation 400 has a first signal pathand a second signal path. The first signal path includes a first LNA 410a connected to a pair of transconductance devices, 422 a and 424 a thatcan selectively route a signal at the output 414 a of the LNA 410 a to afirst band translation device 430 a or a second band translation device430 b. The crosspoint switch with band translation 400 uses thetransconductance devices, for example 422 a and 422 b, to providecurrent-mode switching of the signals.

The first LNA 410 a is configured with a differential input 412 a and adifferential output 414 a. The differential input 412 a of the first LNA410 a can be matched to 75 ohm differential. The differential output 414a of the first LNA 410 a is configured to have a low impedance. Thecrosspoint switch with band translation 400 maximizes signal isolationand minimizes switching transients by connecting high isolationtransconductance devices, 422 a and 424 a, to the output of the firstLNA 410 a. Band translation devices 430 a, 430 b having low inputimpedances are connected to the outputs of the transconductance devices422 a and 424 a.

The differential output 414 a of the first LNA 410 a is connected to thehigh impedance differential inputs of the transconductance devices 422 aand 424 a. The first LNA 410 a can drive both transconductance devices422 a and 424 a because the differential inputs of the transconductancedevices 422 a and 424 a are high impedance.

Each of the transconductance devices 422 a and 424 a includes a controlinput, 423 a and 425 a respectively, that is used to switch thetransconductance device 422 a and 424 a on or off. When the signal fromthe first LNA 410 a is to be routed to the first band translation device430 a, the first transconductance device 422 a is controlled to providea current output to the input of the first and translation device 430 a.Similarly, the second transconductance device 424 a can be controlled toprovide a current output to the input of the second band translationdevice 430 b. One or more transconductance devices, for example 422 aand 424 a connected to an LNA 410 a can simultaneously be enabled suchthat one input, for example a signal at 412 a, can be routed to all bandtranslation devices 430 a and 430 b.

The first band translation device 430 a can selectively frequencytranslate the signal at its input to an output frequency band. The firstband translation device 430 a uses a signal from a first LO 440 a toperform the frequency translation. The first band translation device 430a has a low impedance input and thus, operates as a current summing nodefor the currents from the transconductance devices 422 a and 422 b towhich its input is connected.

A second signal path is configured similar to the first signal path. Asecond LNA 410 b has a differential input 412 b and a differentialoutput 414 b. The signal at the differential output 414 b of the secondLNA 410 b is selectively connected to the first band translation device430 a using a third transconductance device 422 b. The signal at thedifferential output 414 b of the second LNA 410 b is selectivelyconnected to the second band translation device 230 b using a fourthtransconductance device 424 b. The second band translation device 430 boperates in conjunction with a second LO 440 b.

The transconductance devices 422 a, 422 b, 424 a, and 424 b can be anytype of transconductance devices, such as transistors, FETs, and thelike. The transconductance devices 422 a, 422 b, 424 a, and 424 b have ahigh output impedance. Thus, multiple transconductance devices, forexample 422 a and 422 b can selectively provide a signal to the sameband translation device 430 a without the output impedance of the firsttransconductance device 422 a affecting the performance of the othertransconductance device 422 b. The low input impedance band translationdevice 430 a operates as a current summing node.

In an alternative embodiment of the crosspoint switch with bandtranslation 400, the LNA's 410 a and 410 b are omitted and the inputsignals are directly coupled to the inputs of the transconductancedevices 422 a, 422 b, 424 a, and 424 b. The inputs to the first andsecond signal paths can be matched to a predetermined impedance using amatching circuit (not shown) which can be as simple as a resistor placedacross the differential inputs.

FIG. 5 is a functional block diagram of a crosspoint switch with bandtranslation 500 having LNA/band translation device pairs for eachinput/output combination and summing the outputs of the band translationdevices in the current domain. As with the crosspoint switch with bandtranslation devices of FIGS. 2 and 4, the crosspoint switch with bandtranslation 500 can be combined with LNBs in the receiver 180 of FIG. 1.The devices in the crosspoint switch with band translation 500 utilizedifferential signals to minimize noise, but single-ended devices can beused in other embodiments.

Each LNA/band translation pair can selectively provide a signal to anoutput or be controlled to isolate the signal at the input from theoutput. The LNA can be selectively controlled to isolate the signal byremoving the bias, or by reversing the bias on the amplifier. Forexample, the controller in the set top box 160 a of FIG. 1 can receiveuser input and control the bias control pins, labeled A, B, C, and D, toselectively enable or disable the bias to the LNAs 510 a-b, 520 a-b.

A first LNA/band translation device pair includes a first LNA 510 aconnected to a first input 512 a. The first LNA 510 a is controlled toselectively amplify or isolate the input signal based on a signalprovided to its control input 514 a. The output of the first LNA 510 ais connected to a first band translation device 532 having a high outputimpedance. The output of the first band translation device 532 isconnected to a first signal output 540 a.

A second LNA/band translation device pair includes a second LNA 520 ahaving an input connected to the first input 512 a. The controller inthe set top box can control the control input 524 a of the second LNA520 a to selectively amplify or isolate the input signal. The output ofthe second LNA 520 a is connected to a second band translation device534 having a high output impedance. The output of the second bandtranslation device 534 is connected to a second signal output 540 b.

Thus, in order to selectively route a signal from the first input 512 ato the first signal output 540 a, the controller in the set top boxselectively controls the first LNA 510 a to amplify the input signal byproviding an enable signal to the control input, 514 a, on the first LNA510 a. In order to isolate a signal at the first input 512 a from thefirst output 540 a, the first LNA 510 a is selectively controlled toisolate the signal.

A second differential input 512 b is connected to the inputs of a thirdLNA 510 b and a fourth LNA 520 b. The third LNA 510 b is controlled toselectively amplify or isolate the input signal based on a signalprovided to its control input 514 b. The output of the third LNA 510 bis connected to a third band translation device 536 having a high outputimpedance. The output of the third band translation device 536 isconnected to a first signal output 540 a.

Similarly, the fourth LNA 520 b is controlled to selectively amplify orisolate the input signal based on a signal provided to its control input524 b. The output of the fourth LNA 520 b is connected to a fourth bandtranslation device 538 having a high output impedance. The output of thefourth band translation device 538 is connected to a first signal output540 b.

Thus, a signal provided to the second differential input 512 b canselectively be routed to the first or second signal outputs, 540 a or540 b or simultaneously to both signal outputs. In order to route thesignal from the second input 512 b to the first signal output 540 a, acontrol signal is provided to the control input 514 b of the third LNA510 b to enable the third LNA 510 b to amplify the second input signal.In order to route the signal from the second input 512 b to the secondsignal output 540 b, a control signal is provided to the control input524 b of the fourth LNA 520 b to enable the fourth LNA 520 b to amplifythe second input signal.

The outputs of the first and third band translation devices 532, 536 canbe summed at the load if both signals are routed to the first signaloutput 540 a. Similarly, the outputs of the second and fourth bandtranslation devices 534 and 538 can be summed at the load if bothprovide signals to the second signal output 540 b. Thus, by usingcurrent outputs from high impedance devices driving matched impedanceloads, multiple signals can be summed in a common node.

FIG. 6 is another embodiment of a 2×2 crosspoint switch with bandtranslation 600. The specific embodiment is optimized for implementationwithin a single integrated circuit having impedance matched inputs andoutputs. It is evident that the number of inputs or outputs can beexpanded to any other number. The embodiment uses current modeswitching. LNA's having a matched input, variable gain, and a lowimpedance output are used. Signals at a first input 612 a can be routed,using first and second transconductance devices, to one or both outputs670 a and 670 b. Similarly, signals at a second input 612 b can berouted, using third and fourth transconductance devices, to one or bothoutputs 670 a and 670 b.

The 2×2 crosspoint switch with band translation 600 receives the inputsignal at a matched signal input of the low noise amplifiers. The lownoise amplifiers generate intermediate signals at their low impedanceoutputs. The intermediate signals are provided to high impedance inputsof current sources configured as transconductance devices. A controllercan selectively control the transconductance devices to provide anoutput current based in part on the intermediate signal. Additionally,the controller can selectively enable or disable each of thetransconductance devices. For example, the bias to each of thetransconductance device may be controllable to selectively enable ordisable the device. Alternatively, the bias current may be variedlinearly to control the gain of the transconductance devices.Alternatively, the gain may be varied via other means and thetransconductor may be enabled and disabled by other means.

The current output of the transconductance devices can then be receivedat low impedance inputs of band translation devices that can frequencytranslate the current signals from a first frequency band to a secondfrequency band. The band translation devices can have matched impedanceoutputs.

A first signal path is configured to amplify, band translate, and routea first signal to one of two outputs. A first LNA 610 a has adifferential input 612 a configured to accept the first signal. Theinput 612 a of the first LNA 610 a can be a differential input that ismatched to a predetermined impedance, such as 75Ω or 50Ω. Thedifferential output of the first LNA 610 a has an in-phase output 614 aand an inverted output 616 a. The differential output of the first LNA610 a can be a low output impedance, a matched output impedance, or ahigh output impedance. The output impedance of the first LNA 610 a canbe, for example, 200 ohms differential.

The in-phase output 614 a of the first LNA 610 a is connected to a firstemitter follower 622 a that has a low output impedance. The in-phaseoutput 614 a of the first LNA is connected to the base of the firstemitter follower 622 a. The emitter of the first emitter follower 624 ais connected to a current source 624 a that biases the first emitterfollower 624 a. The output of the first emitter follower 624 a isconnected to the in-phase inputs of the differential inputs to first andsecond transconductance devices. The transconductance devices have highinput impedances. The transconductance devices can be bipolar devicesthat can be selectively enabled or disabled by controlling the biascurrents.

Similarly, the inverted output 616 a of the first LNA is connected tothe input of a second emitter follower 626 a. The second emitterfollower 626 a is biased using a current source 628 a connected to itsemitter. The output of the second emitter follower 626 a is connected tothe inverted inputs of the first and second transconductance devices.

Alternatively, the first and second emitter followers, 622 a and 626 a,with their associated current sources, 624 a and 628 a, can beconsidered the low impedance output stage of the first LNA 610 a.

The first transconductance device includes a first transistor 632 a withthe base of the first transistor 632 a serving as the in-phase input ofthe first transconductance device. A first resistor 633 a connects theemitter of the first transistor 632 a to a controllable current source638 a. The base of a second transistor 634 a is used as the invertedinput of the first transconductance device. A second resistor 635 aconnects the emitter of the second transistor 634 a to the controllablecurrent source 638 a.

The controllable current source 638 a provides the bias for thetransistors, 632 a and 634 a of the first transconductance device. Thecontrollable current source 638 a can be selectively enabled or disabledbased on a control signal. The first transconductance device isolates asignal at its input from its output when the controllable current source638 a is disabled, and conversely, provides a current output that can beproportional to the input signal when the controllable current source638 a is enabled.

A first differential buffer amplifier having two transistors 652 a and654 a is used to sum the currents from multiple transconductance devicesand provide a differential signal to the first band translation device660 a.

The first band translation device 660 a is configured with a low inputimpedance and an output impedance matched to a predetermined impedance.For example, the output of the first band translation device 660 a canbe matched to 75. The differential output of the first band translationdevice 660 a is connected to the first signal output 670 a. The firstband translation device 660 a is driven with a first LO 662 a. The firstLO 662 a frequency can be tunable to allow the frequency translation ofthe first band translation device 662 a to be tuned. Alternatively theoutput frequency of the first LO 662 a can be fixed. The first bandtranslation device 662 a can be configured to frequency translate thesignal or to pass the signal without frequency translation.

The first LNA 610 a also provides a signal that can be selectivelyrouted to a second output 670 b. The differential outputs from the firstand second emitter followers, 622 a and 626 a are connected to thedifferential inputs of a second transconductance device.

The base of a first transistor 642 a in the second transconductancedevice is connected to the in-phase output from the first emitterfollower 622 a. The base of a second transistor 644 a in the secondtransconductance device is connected to the inverted output from thesecond emitter follower 626 a. Resistors 643 a and 645 a connect theemitters of the first and second transistors 642 a and 644 a to acontrollable current source 648 a that selectively provides bias to thefirst and second transistors 642 a and 644 a. The secondtransconductance device provides an output current when the controllablecurrent source 648 a is enabled. Conversely, the second transconductancedevice does not provide an output current when the controllable currentsource 648 a is disabled.

The differential output from the second transconductance device isconnected to the differential input of a second differential bufferamplifier. The second differential buffer amplifier includes twotransistors 652 b and 654 b and is used to sum the currents frommultiple transconductance devices and provide a differential signal tothe second band translation device 660 b .

The output of the second differential buffer amplifier is connected tothe differential input of a second band translation device 660 b. Thesecond band translation device 660 b has with a low input impedance andan output impedance matched to a predetermined impedance such as 75. Thedifferential output of the second band translation device 660 b isconnected to the second signal output 670 b. The second band translationdevice 660 b is driven with a second LO 662 b. The second LO 662 bfrequency can be tunable to allow the frequency translation of thesecond band translation device 662 b to be tuned. Alternatively theoutput frequency of the second LO 662 b can be fixed. The second bandtranslation device 662 b can be configured to frequency translate thesignal or to pass the signal without frequency translation.

The second signal input 612 b is connected to the second LNA 610 b andthrough third and fourth transconductance devices to the first andsecond differential buffer amplifiers in a configuration that is similarto the path from the first signal input 612 a to the differential bufferamplifiers.

The second signal input 612 b is connected to the input of the secondLNA 610 b. The differential output of the second LNA is connected to apair of emitter followers, one emitter follower for each of the signaloutputs of the second LNA 610 b.

The in-phase LNA output 614 b is connected to a first emitter follower622 b that includes a first current source 624 b connected to itsemitter to provide a bias. The inverted LNA output 616 b is connected toa second emitter follower 626 b that includes a second current source628 b connected to its emitter to provide a bias.

The output of the first emitter follower 622 b is connected to thein-phase inputs of third and fourth transconductance devices. The outputof the second emitter follower 626 b is connected to the inverted inputsof the third and fourth transconductance devices.

The third transconductance device includes first and second transistors632 b and 634 b arranged in a differential configuration. The base ofthe first transistor 632 b is the in-phase input of the transconductancedevice and the base of the second transistor 634 b is the inverted inputof the third transconductance device. The emitters of the first andsecond transistors, 632 b and 634 b, are connected via first and secondresistors, 633 b and 635 b, to a controllable current source 638 b. Thecontrollable current source selectively enables or disables the thirdtransconductance device. The collectors of the first and secondtransistors, 632 b and 634 b, are connected to the differential inputsof the first differential buffer amplifier.

Similarly, the fourth transconductance device includes first and secondtransistors 642 b and 644 b arranged in a differential configuration.The base of the first transistor 642 b is the in-phase input of thetransconductance device and the base of the second transistor 644 b isthe inverted input of the fourth transconductance device. The emittersof the first and second transistors, 642 b and 644 b, are connected viafirst and second resistors, 643 b and 645 b, to a controllable currentsource 648 b. The controllable current source 648 b selectively enablesor disables the fourth transconductance device. The collectors of thefirst and second transistors, 642 b and 644 b, are connected to thedifferential inputs of the second differential buffer amplifier. Ofcourse, the transconductance devices shown in FIG. 6 only representembodiments of typical transconductance devices. Other embodiments oftransconductance devices may be used in other embodiments.

Thus, various crosspoint switch with band translation devices have beendisclosed. The devices can be implemented in single integrated circuitsand can be configured to switch any number, N, of inputs to any number,M, outputs. The devices can be configured to perform voltage modeswitching of signals or current mode switching of signals. One or moreinput signals can be routed to the same signal output. Additionally, oneinput signal can be routed to one or more signal outputs. Additionally,the device can be configured to selectively perform frequency bandtranslation of the input signals. One or more of the crosspoint switchwith band translation devices can be combined with LNBs to provide areceiver for a signal distribution system. Alternatively, the LNB63 scan be remote from the crosspoint switch with band translation. The useof crosspoint switch with band translation devices allows greaterflexibility in signal routing within the signal distribution system.

The switch configuration provides input and output signal isolation. Theconfiguration of input and output impedances for the intermediate stagesof the crosspoint switch with band translation ensures minimal switchingtransients. The configuration of input and output impedances for theintermediate stages is based in part on whether voltage mode or currentmode switching is implemented. A controllable current source can be usedto selectively enable and disable transconductance devices to enableswitching of signals. Differential signals can also be used to furtherminimize noise induced onto the desired signals.

Electrical connections, couplings, and connections have been describedwith respect to various devices or elements. The connections andcouplings can be direct or indirect. A connection between a first andsecond device can be a direct connection or can be an indirectconnection. An indirect connection can include interposed elements thatcan process the signals from the first device to the second device.

Those of skill in the art will understand that information and signalscan be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that can be referenced throughout theabove description can be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill will further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the embodiments disclosed herein can be implemented aselectronic hardware, computer software, or combinations of both. Toclearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled persons can implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein can be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor can be a microprocessor, but in thealternative, the processor can be any processor, controller,microcontroller, or state machine. A processor can also be implementedas a combination of computing devices, for example, a combination of aDSP and a microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein can be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module can reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium. An exemplary storage mediumcan be coupled to the processor such the processor can read informationfrom, and write information to, the storage medium. In the alternative,the storage medium can be integral to the processor. The processor andthe storage medium can reside in an ASIC.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, the invention is not intended to be limited tothe embodiments shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

1. An integrated circuit, having N-input by M-output crosspoint switchwith band translation, for use in an RF signal distribution system, theintegrated circuit comprising: an N input switch configured to route aninput signal at any one of the N inputs to any one of the M outputs,with each of the N inputs having a high input impedance; and M bandtranslation devices, each of the M band translation devices connected toan output of the N input switch and configured to selectively frequencytranslate or pass through a signal from the output of the N inputswitch.
 2. The integrated circuit of claim 1, wherein the N input switchcomprises N groups of M switches, with each group of M switches havinginputs connected to a separate one of the N inputs, each group of Mswitches further having each of the M switch outputs connected to aseparate one of the M band translation devices.
 3. The integratedcircuit of claim 2, wherein each switch in the N groups of M switchescomprises a voltage mode switch and wherein each of the band translationdevices has a high impedance input.
 4. The integrated circuit of claim2, wherein each switch in the N groups of M switches comprises a currentmode switch and wherein each of the band translation devices has a lowimpedance input.
 5. The integrated circuit of claim 2, wherein eachswitch in the N groups of M switches comprises a transconductancedevice.
 6. The integrated circuit of claim 2, wherein each switch in theN groups of M switches is selectively enabled or disabled based on acontrol signal.
 7. The integrated circuit of claim 2, wherein eachswitch in the N groups of M switches provides greater than 30 dB ofsignal isolation in a disabled state.
 8. The integrated circuit of claim1, further comprising N low noise amplifiers (LNAs), with each LNAhaving an output connected to a separate input on the N input switch. 9.The integrated circuit of claim 1, wherein the N input switch and the Mband translation devices include differential signal inputs anddifferential signal outputs.
 10. The integrated circuit of claim 1,wherein each of the M band translation devices is configured tofrequency translate a signal from a first RF frequency band to a secondRF frequency band.
 11. An integrated circuit having a crosspoint switchwith band translation for use in an RF signal distribution system, theintegrated circuit comprising: a first low noise amplifier (LNA) havinga differential input and a low impedance differential output; a firsttransconductance device having a differential output and a highimpedance differential input connected to the low impedance differentialoutput of the first LNA; a second transconductance device having adifferential output and a high impedance differential input connected tothe low impedance differential output of the first LNA; a first bandtranslation device having a differential output and a low impedancedifferential input connected to the differential output of the firsttransconductance device; and a second band translation device having adifferential output and a low impedance differential input connected tothe differential output of the second transconductance device.
 12. Theintegrated circuit of claim 11, wherein the first transconductancedevice comprises a controllable current source configured to selectivelyenable and disable the first transconductance device.
 13. A method ofrouting signals in a reconfigurable signal distribution system, themethod comprising: receiving a signal at a matched impedance input of alow noise amplifier (LNA) having a low output impedance; selectivelyrouting an output voltage of the LNA, using a first transconductancedevice having a high impedance input, as a current at an output of thefirst transconductance device; selectively routing an output voltage ofthe LNA, using a second transconductance device having a high impedanceinput, as a current at an output of the second transconductance device;and frequency translating a signal at the output of the firsttransconductance device from a first RF frequency band to a second RFfrequency band.
 14. A method of routing signals in a reconfigurablesignal distribution system, the method comprising: receiving an inputsignal at a matched impedance input of a input device; generating anintermediate signal, based in part on the input signal, at the lowimpedance output of the input device; providing the intermediate signalto a high impedance input of a current source; selectively enabling thecurrent source to provide an output current signal based in part on theintermediate signal; receiving the output current signal at a lowimpedance input of a band translation device; and frequency translatingthe output current signal from a first frequency band to a secondfrequency band.